From b462579b2b86a8f5230543cadd3a4836be27baf7 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Fri, 19 Jan 2024 13:34:32 +0100 Subject: netfilter: nf_tables: restrict anonymous set and map names to 16 bytes nftables has two types of sets/maps, one where userspace defines the name, and anonymous sets/maps, where userspace defines a template name. For the latter, kernel requires presence of exactly one "%d". nftables uses "__set%d" and "__map%d" for this. The kernel will expand the format specifier and replaces it with the smallest unused number. As-is, userspace could define a template name that allows to move the set name past the 256 bytes upperlimit (post-expansion). I don't see how this could be a problem, but I would prefer if userspace cannot do this, so add a limit of 16 bytes for the '%d' template name. 16 bytes is the old total upper limit for set names that existed when nf_tables was merged initially. Fixes: 387454901bd6 ("netfilter: nf_tables: Allow set names of up to 255 chars") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 4b55533ce5ca2c..02f45424644b4d 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -24,6 +24,7 @@ #include #define NFT_MODULE_AUTOLOAD_LIMIT (MODULE_NAME_LEN - sizeof("nft-expr-255-")) +#define NFT_SET_MAX_ANONLEN 16 unsigned int nf_tables_net_id __read_mostly; @@ -4413,6 +4414,9 @@ static int nf_tables_set_alloc_name(struct nft_ctx *ctx, struct nft_set *set, if (p[1] != 'd' || strchr(p + 2, '%')) return -EINVAL; + if (strnlen(name, NFT_SET_MAX_ANONLEN) >= NFT_SET_MAX_ANONLEN) + return -EINVAL; + inuse = (unsigned long *)get_zeroed_page(GFP_KERNEL); if (inuse == NULL) return -ENOMEM; -- cgit 1.2.3-korg